646 MR FRANK J. COLE ON THE 



(b) Superficial ophthalmic* — This nerve is of exceptional interest, since it does 

 not fuse with the nerve of the same name from the Vllth, and its distribution may 

 therefore be ascertained without any of the doubt necessarily attached to its distribu- 

 tion in Elasmobranch fishes. It arises in the orbit from the Gasserian ganglion, and 

 courses straight upwards, and, after crossing the superficial ophthalmic of the Vllth, 

 runs straight forwards, above the latter, to be distributed to the skin over and in front 

 of the orbital region. We may therefore conclude with certainty that this branch of 

 the Vth does not innervate any sense organs of the lateral line. 



The following variations of this nerve were noticed (my two specimens may be 

 termed respectively A and B) : — 



(1) May be quite distinct from the superficial ophthalmic of the Vllth, as on left 



side of A. 



(2) May send, as it passes over it, two very small bundles of fibres to the facial 



nerve above, as on right side of A. 



(3) May completely fuse with the facial, as on left side of B (right not investi- 



gated). Figured in this condition by Stannius. 



From material I have since examined, and which was kindly placed at my disposal 

 by Professor G. B. Howes, I am inclined to believe that 1 and 2 represent the normal 

 condition. 3 I have only seen once, but it is figured and referred to by Stannius 

 as an anastomosis between two divisions of the Vth [i.e., his Vth). In a dissection of 

 the nerves of Callorhynchus which Professor Howes has in his laboratory, no such 

 connection between the Vth and Vllth is to be seen. 3, of course, represents the 

 condition found in Elasmobranchs. 



Maxillary and mandibular. — The Vth divides into maxillary and mandibular 

 branches at a level slightly in front of the optic foramen. The mandibular, as figured 

 by Stannius, dips down at once. There is a large nerve given off at the same place, 

 which seems to come from the maxillary, but which, when dissected along carefully, is 

 found to arise mostly from the mandibular. It courses straight forwards along the floor 

 of the orbit, and becomes buried in the expanded dorsal base of the masseter muscle 

 of the lower jaw, of which it constitutes the principal nerve supply. 



(c) Maxillary. — This nerve, whilst in the orbit, gives off a posterior motor branch, 

 and then, leaving the orbit, sends two or three branches posteriorly to the masseter. It 

 then receives the twigs from the outer buccal previously described, and courses straight 

 down towards the upper jaw, which, as is well known, is in Chimsera fused with the 

 cranium. Before, however, reaching the lower jaw, it gives off several motor branches 

 from its posterior border. Arrived at the jaw, it dips down suddenly, but, before doing 

 so, sends numerous twigs to the levator of the upper lip. It then dips down under the 



* According to Dixon (infra), the superficial ophthalmic of the Vth of fishes possibly represents the frontal 

 nerve of mammals. 



